Transient reduction and activation of circulating dendritic cells in patients with acute myocardial infarction.

Background: Dendritic cells (DCs) are highly potent professional antigen-presenting cells that play a central role in initiating the primary immune response. Accumulating evidence suggests that immune-mediated inflammation plays an important role in the pathophysiology of AMI, but the mechanism that triggers such immune responses is unknown.

Methods: Using multi-color flow-cytometry, we determined the numbers of circulating myeloid DCs (mDCs) and plasmacytoid DCs (pDCs) in patients with AMI (n = 26) or stable angina pectoris (SAP) (n = 19), and in age-matched control subjects (n = 19). The DC activation markers CD40 and CD83 were also measured.

Results: On admission, circulating mDC and pDC counts were significantly lower in AMI patients compared to control subjects and SAP patients (mDC, P < 0.01; pDC, P < 0.05). The activation markers of mDCs in AMI patients were significantly higher and returned to the levels of control subjects or SAP patients 3 days after AMI (mDC, P < 0.05; pDC, P < 0.05). Reductions of circulating mDC and pDC numbers were restored 7 days after the onset of AMI. Furthermore, we found that the recovery of the circulating DC numbers 14 days after AMI was correlated with the alterations of creatine kinase-MB (CK-MB) (mDC, r = 0.48, P < 0.05; pDC, r=0.52, P < 0.01) and brain natriuretic peptide (BNP) (mDC, r = 0.53, P < 0.01; pDC, r = 0.51, P < 0.01).

Conclusion: Our findings suggest that the transient reduction and activation of circulating DCs may play important roles in the pathophysiology of myocardial injury after AMI.